The Intercity Materieel or ICM (English – Intercity Material or Intercity Rolling Stock) is an electric multiple unit (EMU) train type operated by the Nederlandse Spoorwegen in the Netherlands. The train received the nickname Koploper, because it had a so-called "walk through head". After these trains were modernized, the "walk through heads" were removed. The modernized train sets are referred to as Intercity Materieel Modern (ICMm). The prototypes were built in 1977, with full-scale production lasting from 1983 to 1994 by Talbot. The first train sets came into service in 1977. The trains run daily on the Dutch rail network and, together with the VIRM, form the most important equipment on services connecting the Randstad with the rest of the country. Names Intercity Materieel Koploper ICM ICMm ICM is short for "Intercity Materieel", which means "Intercity rolling stock". The "m" in ICMm indicates that it is modernized. General information The trains are designed for long-distance intercity services. Their maximum allowed operating speed is 140km/h, although their engines are designed to reach a top speed of 180km/h. Their cabs are on the roof, which initially allowed through gangways between sets when coupled together, though the gangways were removed during their refurbishment, as they were deemed too unreliable. Refurbishment of sets began in late 2006 and was completed in 2011. The trains have compartments in the 1st class accommodation. Subseries ICM-0 In 1977, a prototype batch numbered 4001–4007 were delivered. They first operated between Eindhoven and Venlo and then later between Amsterdam and Nijmegen. These were taken out of service in 2003, as NS considered them to be too expensive to keep running. ICM-1 and ICM-2 These were numbered 4011–4097 and were first introduced into service in 1983. All were delivered by 1990. These had been adjusted to remove the faults of the ICM-0. 4051–4097 are Thyristor controlled. ICM-3 and ICM-4 Between 1990 and 1994, 50 4-car units were delivered, numbered 4201 – 4250. These have track brakes. Between 1996 and 2007, unit 4231 had a full coach converted to 1st class and was renumbered 4444. This unit only operated one train a day between Groningen and The Hague. It has since been converted back to a regular carriage, but it continued carrying number 4444 at first. After its revision in 2011, this unit was given its original number (4231) back. Walk through head The train's name Koploper means "Frontrunner" but the